Obesity is major public health issues not only for the EU, USA, Japan but also for the world in general. It is associated with a number of serious diseases including diabetes, dyslipidemia, hypertension, cardiovascular and cerebrovascular diseases. Although the underlying mechanisms are not yet fully understood, the impairement of insulin action in target tissues by accumulation of excess lipids is generally regarded as a key mechanism linking obesity to secondary pathologies (G. Wolf, Nutrition Reviews Vol. 66(10):597-600; D B Savage, K F Petersen, G I Shulman, Physiol Rev. 2007; 87:507-520). Therefore, understanding of cellular lipid metabolism in insulin target tissues is crucial in order to elucidate the development of diseases associated with obesity.
A central event in lipid metabolism is the generation of malonyl-CoA via carboxylation of acetyl-CoA by the two mammalian ACC isoforms ACC1 (ACC-alpha, also termed ACCA) and ACC2 (ACC-beta, also designated ACCB) (Saggerson D. Annu Rev Nutr. 2008; 28:253-72). The malonyl-CoA generated is used for de novo fatty acid synthesis and acts as inhibitor of CPT-1, thereby regulating mitochondrial fatty acid oxidation. Furthermore, malonyl-CoA is also described to act centrally to control food intake, and may play an important role in controlling insulin secretion from the pancreas (G D Lopaschuk, J R Ussher, J S Jaswal. Pharmacol Rev. 2010; 62(2):237-64; D Saggerson Annu Rev Nutr. 2008; 28:253-72), further coordinating the regulation of intermediary metabolism.
Therefore ACC1 and ACC2 have been shown to be major regulators of fatty acid metabolism and are presently considered as an attractive target to regulate the human diseases of obesity, diabetes and cardiovascular complications (S J Wakil and L A Abu-Elheiga, J. Lipid Res. 2009. 50: S138-S143; L. Tong, H J Harwood Jr. Journal of Cellular Biochemistry 99:1476-1488, 2006).
As a result of its unique position in intermediary metabolism, inhibition of ACC offers the ability to inhibit de novo fatty acid production in lipogenic tissues (liver and adipose) while at the same time stimulating fatty acid oxidation in oxidative tissues (liver, heart, and skeletal muscle) and therefore offers an attractive modality for favorably affecting, in a concerted manner, a multitude of cardiovascular risk factors associated with obesity, diabetes, insulin resistance, and the metabolic syndrome (L. Tong, H J Harwood Jr. Journal of Cellular Biochemistry 99:1476-1488, 2006; Corbett J W, Harwood J H Jr., Recent Pat Cardiovasc Drug Discov. 2007 Nov.; 2(3):162-80). In addition ACC inhibitors also have the potential to intervene in the progression of diseases that result from the rapid growth of malignant cells or invading organisms that are dependent on endogenous lipid synthesis to sustain their rapid proliferation. The potential of ACC inhibitors as antifungal agents and as antibacterial agents is well documented (L. Tong, H J Harwood Jr. Journal of Cellular Biochemistry 99:1476-1488, 2006). Furthermore, de novo lipogenesis is known to be required for growth of many tumor cells and ACC up-regulation has been recognized in multiple human cancers, promoting lipogenesis to meet the need of cancer cells for rapid growth and proliferation (C Wang, S Rajput, K Watabe, D F Liao, D Cao Front Biosci 2010; 2:515-26). This is further demonstrated in studies using ACC inhibitors which induced growth arrest and selective cytotoxicity in cancer cells and by RNA interference-mediated knock-down of ACC which inhibited growth and induced apoptosis in different types of cancer cells. Furthermore, ACC1 associates with and is regulated by the breast cancer susceptibility gene 1 (BRCA1). Commonly occurring BRCA1 mutations lead to ACC1 activation and breast cancer susceptibility (C Wang, S Rajput, K Watabe, D F Liao, D Cao Front Biosci 2010; 2:515-26).
Furthermore in central nervous system disorders including but not limited to Alzheimer's disease, Parkinson disease and epilepsy, impairements in neuronal energy metabolism have been described (Ogawa M, Fukuyama H, Ouchi Y, Yamauchi H, Kimura J, J Neurol Sci. 1996; 139(1):78-82). Interventions targeting this metabolic defect may prove beneficial to the patients. One promising intervention is therefore to provide the glucose-compromised neuronscerebral brain neurons with ketone bodies as an alternative substrate (S T Henderson Neurotherapeutics, 2008, 5:470-480; L C Costantini, L J Barr, J L Vogel, S T Henderson BMC Neurosci. 2008, 9 Suppl 2:S16; K W Baranano, A L Hartman. Curr Treat Options Neurol. 2008; 10:410-9). ACC inhibition leading to increased fatty acid oxidation may thereby result in increases in the blood levels of ketone bodies thereby providing an alternative energy substrate for the brain.
Preclinical and clinical evidence indicates that ketone bodies can provide neuroprotective effects in models of Parkinson's disease, AD, hypoxia, ischemia, amyotrophic lateral sclerosis and glioma (L C Costantini, L J Barr, J L Vogel, S T Henderson BMC Neurosci. 2008, 9 Suppl 2:S16) and improved cognitive scores in Alzheimers Diseases patients (M A Reger, S T Henderson, C Hale, B Cholerton, L D Baker, G S Watson, K Hydea, D Chapmana, S Craft Neurobiology of Aging 25 (2004) 311-314). The end result of increased ketone levels is an improvement in mitochondrial efficiency and reduction in the generation of reactive oxygen species (for reviews see L C Costantini, L J Barr, J L Vogel, S T Henderson BMC Neurosci. 2008, 9 Suppl 2:S16; K W Baranano, A L Hartman. Curr Treat Options Neurol. 2008; 10:410-9).